Casing degasser tool

ABSTRACT

A casing degasser tool (CDT) is provided which is adapted to be inserted into production piping such as casing, slotted liners, or production tubing for use during well completion. The CDT comprises a body having a top end, a bottom end and an outer surface, at least one sealing element surrounding a portion of the outer surface of the body and a connection means located at or near the top end of the body for connecting a wire line or other pulling device to the CDT to assist in positioning the CDT within the production piping and for pulling the CDT through the length of the production piping. The CDT can be used when adding joints of production piping to prevent hydrocarbons from flowing to the surface of the well.

This application claims the benefit of U.S. Provisional Application No.60/521,523, filed May 13, 2004.

FIELD OF THE INVENTION

The present invention relates to an apparatus and method useful for wellcompletion of a wellbore containing hydrocarbons. In particular, thepresent invention relates to an apparatus adapted to be inserted intoproduction piping, such as casing, slotted liners, or tubing, to controlthe flow of fluids from the reservoir through the production pipingduring well completion operations and further relates to a process usingsaid apparatus for running joints of production piping into a wellboreto form a completed well.

BACKGROUND OF INVENTION

Current technology uses kill fluids to stop the flow of reservoir fluids(e.g. hydrocarbons) so that well completion operations such as runningproduction piping in the wellbore or installing a wellhead assembly atsurface can be accomplished without the presence of hydrocarbons.Conventional kill fluids known in the art are typically aqueous liquidssuch as water or weighted fluids such as drilling mud. The kill fluidapplies a hydrostatic pressure against the reservoir fluid, whichtypically is greater than the pressure exerted by the reservoir fluidattempting to intrude into the wellbore.

This overbalanced hydrostatic pressure, however, can cause damage toreservoirs, in particular, to reservoirs containing swelling clays orreservoirs having a pressure well below the hydrostatic pressure of thekill fluid being used. Hydrocarbon reservoirs with high permeability andporosity can also be damaged with the use of kill fluids.

The present invention provides an apparatus and method for carrying outcompletion activities without the need to kill the flow of hydrocarbonsby means of kill fluids.

SUMMARY OF THE INVENTION

A casing degasser tool (CDT) is provided which is adapted to be insertedinto production piping such as casing, slotted liners, or productiontubing. One CDT embodiment comprises a body having a top end, a bottomend and an outer surface, and at least one expandable sealing elementsurrounding a portion of the outer surface of said body. The expandablesealing element can be formed from a material such as expandable rubber,rubber and steel, fiberglass or other composite material, and can beexpanded such that it provides a fluid tight seal with the inside wallof the production piping. For example, the sealing element can be aninflatable ring wherein the inflatable ring expands or contracts bypumping fluids into or out of the inflatable ring.

In another embodiment, the CDT comprises at least one sealing elementsurrounding a portion of the outer surface of said body, wherein eachsealing element has a fixed dimension, which dimension depends upon theinner diameter of the completion piping for which it is designed. Thus,in this embodiment, the sealing element dimension can vary for each typeof production tubing but will still provide a fluid tight seal when theCDT is inserted therein. Hence, it is understood that the sealingelement of the CDT can come in different sizes to ensure that the CDTalways fits snuggly inside the production piping having a range ofdifferent inside diameters.

The body further comprises a connection means located at or near the topend of the body for connecting a wire line or other pulling device tothe CDT to assist in positioning the CDT within the production pipingand for pulling the CDT through the length of the production piping.

In one embodiment, the body further comprises an inner cavity extendingthrough the bottom end of the body so that the bottom end of the body isin fluid communication with the inside of the production piping when theCDT is inserted therein. In this embodiment, the body may furthercomprise a pressure relief fitting and/or a pressure gauge fitting.

The pressure relief fitting has one end in fluid communication with saidinner cavity and an opposite end for connecting a pipe or hose theretoto bleed off hydrocarbons to the surface when necessary during a wellcompletion operation. A flow prover can also be connected to thepressure relief fitting instead of a pipe or hose to test for wellproduction capability at the completion of running the productionpiping. The pressure relief fitting further comprises a sealing meansfor keeping the pressure relief fitting sealed until the pipe, hose orflow prover is connected thereto.

Similarly, the pressure gauge fitting has one end in fluid communicationwith said inner cavity and an opposite end for connecting a pressuregauge or other instrumentation package thereto for measuring downholepressure. The pressure gauge fitting further comprises a sealing meansfor keeping the pressure gauge fitting sealed until the pressure gaugeor other instrumentation package is connected thereto.

A process of running joints of production piping into a wellbore thatcontains flowing hydrocarbons, which uses the CDT of the presentinvention, is also provided. The process comprises placing the CDTinside a first joint of production piping, said production piping havinga top end and a bottom end, and lowing the production piping into thewellbore bottom end first. The CDT is preferably positioned near the topend of the first joint of production piping and at least one sealingelement is in frictional engagement with the inside wall surface of theproduction piping to provide a fluid tight seal.

The process further comprises adding a second joint of productionpiping, said second joint of production piping also having a top end anda bottom end, to the first joint of production piping by coupling thebottom end of said second production piping to the top end of the firstproduction piping with coupling means known in the art. A wire line orother pulling device is then attached to the CDT by first passing itthrough the second joint of production piping and then attaching it tothe connection means located at or near the top of the body of the CDT.

Finally, the CDT is pulled through the top end of the first joint ofproduction piping, through the bottom end of said second joint ofproduction piping and into the second joint of production piping. Thewire line or other pulling device that is connected to the top end ofthe body of the CDT is then removed and the process is repeated untilall joints of production piping have been coupled together.

To aid in the pulling of the CDT through the production piping, alubricant such as pipe thread dope may be added to the inside surface ofthe production piping.

In another embodiment of the process, the CDT can simply remainpositioned in the first joint of production piping at all times duringthe addition of each new joint of production piping and the CDT pulledthrough all production piping at once when the well is completed.

In one embodiment, when the running of the production piping is complete(i.e., all of the joints of production piping have been connectedtogether), well production capability can be tested by connecting a flowprover to the pressure relief fitting of the CDT. The CDT can then beremoved by means of the wire line or other pulling device that isconnected to the CDT.

In another embodiment, the process of running production casing intowellbore further comprises periodically checking the downhole pressureby means of a pressure gauge attached to the pressure gauge fitting ofthe CDT. In another embodiment, the process further comprises bleedingbuilt up pressure from the wellbore, should the downhole well pressurestarts to become a concern, by attaching a hose or pipe to the pressurerelease fitting of the CDT. The pressure then can be bled down byattaching the opposite end of the hose or pipe to a blewie line andallowing the built up hydrocarbons in the well to flow into a flarestack, a tank or a pit.

This invention may have one or more of the following advantages over theuse of kill fluids to stop the flow of hydrocarbons during completionoperations:

-   -   (1) time and money can be saved because there is no need to use        kill fluids;    -   (2) in low and under pressure reservoirs there is less formation        damage as compared to the damage caused as a result of the        hydrostatic weight of the kill fluid;    -   (3) in dehydrated and clay swelling reservoirs there are no        fluids to cause damage;    -   (4) it provides an alternative method to using a snubbing unit;    -   (5) it allows reverse circulated center discharge drilled wells        to be completed without having to kill the well;    -   (6) wellbores can be safely bled down prior to the installation        of the wellhead without using kill fluids;    -   (7) well production capability can be tested by connecting a        flow prover to the pressure relief fitting at the completion of        running the production piping; and    -   (8) slotted casing and liners can be run into the wellbore        without the need to kill the well.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic of the casing degasser tool of the presentinvention.

FIG. 2 is a schematic of the casing degasser tool inside a joint ofproduction piping.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an embodiment of the present invention.Casing degasser tool 15 comprises a body 7 having a closed top end 2, anopen bottom end 4 and an inner cavity 8. Disposed around the outsidesurface 13 of body 7, at or near bottom end 4, are a plurality ofsealing elements 11, formed from a material such as rubber or the like.When casing degasser tool 15 is placed inside a joint of productionpiping, sealing elements 111 provide a fluid tight seal with the insidewall of the production piping.

Sealing elements 11 may also be made of expandable rubber and the likeso that sealing element 11 can be expanded by means of pumping fluid orair therein or by means of an electric current. This assists in thefrictional engagement of the sealing element with the inside wall of theproduction piping to ensure a fluid tight seal. Further, the sealingelement can then be contracted slightly to facilitate the pulling of thecasing degasser tool 15 through the production piping.

At or near top end 2 is connection means 1 to which a wire line or otherpulling devices known in the art can be attached for positioning thecasing degasser tool 15 within the joint of production piping and forpulling the casing degasser tool 15 through the joint of productionpiping.

The top end 2 of body 7 further comprises pressure relief fitting 5having threaded end 9, which is in fluid communication with the innercavity 8. Pressure relief fitting 5 comprises a sealing means (notshown), which seals the pressure relief fitting 5 until a pipe, or hose(shown as pipe 19 in FIG. 2) is connected to pressure relief fitting 5by thread means. The pressure relief fitting 5 and pipe or hoseconnected thereto are used to bleed off hydrocarbons from the wellboreto the surface of the well, when necessary during a well completionoperation. It is understood that a flow prover (not shown) or otherinstrumentation can also be connected to the pressure relief fitting 5by thread means for testing well production capability after wellcompletion.

Casing degasser tool 15 further comprises pressure gauge fitting 3having threaded end 10, which is in fluid communication with the innercavity 8. Pressure gauge fitting 3 comprises a sealing means (notshown), which seals the pressure gauge fitting 3 until a pressure gaugeor other instrumentation package is attached thereto by thread means formeasuring downhole pressure.

FIG. 2 schematically illustrates casing degasser tool 15 when it issituated inside production piping 21 and said production piping 21 issituated within a wellbore. Sealing elements 111 of casing degasser tool15 are shown in frictional engagement with the inside wall 23 ofproduction piping 21 to create a tight fluid seal. Reservoirhydrocarbons 13 are thus prevented from flowing out of production casing21 by sealing element 11. Further, top end 2 of casing degasser tool 15is closed so as to prevent the flow of hydrocarbons through the innercavity 8 of casing degasser tool 15. Finally, pressure gauge fitting 3and pressure relief fitting 5 are also in the sealed position, unlesspipe, tubing, pressure gauges and other instrumentation are connectedthereto, and thus hydrocarbons cannot escape therethrough.

A surface control system comprising a surface blowout preventor (notshown) can also be used in combination with the present invention. Asurface blow out preventor will prevent the flow of any hydrocarbonsthat may escape on the outside of the production piping through theannulus formed between the outer wall of the production piping and thewellbore wall during well completion.

Once a new joint of production piping is added to existing productionpiping 21, wire line 6 is fed through the new joint of production pipingand through production piping 21 and attached to connection means 1.Casing degasser tool 15 is then pulled first through the top ofproduction piping 21 and then through the bottom of the newjoint ofproduction casing so as to position casing degasser tool 15 preferablyin the upper portion of the new piece of production casing. It isunderstood that during the addition of each joint of production casing,wire line 6 is first removed and then reattached to pull the casingdegasser tool 15 into the newly added joint of production piping.

In the alternative, casing degasser tool 15 can remain situated in thefirst joint of production piping until all subsequent joints ofproduction piping have been added. Wire line 6 is then threaded throughall interconnected joints of production piping and attached toconnection means 1. Casing degasser tool 15 is then pulled through alljoints of production piping upon well completion.

To facilitate the movement of the casing degasser tool 15 throughproduction piping, sealing element 11, if expandable, may be slightlycontracted to allow casing degassing tool 15 to move more freely throughthe production piping. In the alternative, if sealing element 11 is notexpandable, a lubricant such as pipe thread dope may be added to theinside surface of each joint of production piping to facilitate themovement of the degasser tool 15 through the production piping.

Pressure of formation 27 is monitored by connecting a proper pressuregauge (not shown) to pressure gauge fitting 3. When necessary to bleedoff pressure from formation 27, hose or pipe 19 is connected to pressurerelief fitting 5 and hydrocarbons 13 are flared through a blewie line(not shown) attached to the opposite end of pipe 19 or put into tank orpit (not shown). In the alternative, a flow prover (not shown) can beconnected to pressure relief fitting 5 at the completion of running theproduction piping to test for well production capability.

While the foregoing is directed to one embodiment of the presentinvention, other and further embodiments of the invention may be devisedwithout departing from the basic scope thereof. It is intended that theappended claims cover all such modifications and variations as fallwithin the true spirit and scope of the invention.

1. A casing degasser tool adapted to be inserted into a joint ofproduction piping, the production piping having an inner wall, forpreventing the flow of hydrocarbons through the production tubing duringwell completion, comprising: (a) a body having a top end, a bottom endand an outer surface; (b) at least one sealing element surrounding theouter surface of the body; and (c) a connection means located at or nearthe top end of the body for connecting a wire line or other pullingdevice to the casing degasser tool; whereby when the casing degassertool is inserted into the production piping, the sealing element is infrictional engagement with the inner wall of the production piping. 2.The casing degasser tool as claimed in claim 1 wherein the sealingelement is expandable.
 3. The casing degasser tool as claimed in claim 1wherein the sealing element comprises an inflatable ring.
 4. The casingdegasser tool as claimed in claim 3 wherein the inflatable ring expandsor contracts by pumping fluids into or out of the inflatable ring. 5.The casing degasser tool as claimed in claim 1 wherein the body furthercomprises an inner cavity extending through the bottom end of the bodyso that the inner cavity is in fluid communication with the productionpiping.
 6. The casing degasser tool as claimed in claim 5 wherein thebody further comprises a pressure relief fitting having one end in fluidcommunication with the inner cavity and an opposite end adapted to befitted to a pipe or hose for bleeding off the hydrocarbons.
 7. Thecasing degasser tool as claimed in claim 5 wherein the body furthercomprises a pressure gauge fitting having one end in fluid communicationwith the inner cavity and an opposite end adapted to be fitted to apressure gauge for measuring downhole pressure or a flow prover fortesting well production capability.
 8. A process for running joints ofproduction piping into a wellbore containing flowing hydrocarbons,comprising: (a) positioning a casing degasser tool as claimed in any ofclaims 1 to 7 inside a first joint of production piping, the first jointof production piping having a top end, a bottom end and an inner wall,such that the sealing element of the casing degasser tool is infrictional engagement with the inner wall of the first productionpiping; (b) lowering the first joint of production piping into thewellbore bottom end first; (c) adding a second joint of productionpiping, the second joint of production piping having a top end, a bottomend and an inner wall, to the first joint of production casing bycoupling the bottom end of the second joint of production piping to thetop end of the first joint of production piping with coupling means; (d)attaching a pulling device to the connection means of the casingdegasser tool; and (e) pulling the casing degasser tool through the topend of the first joint of production piping, through the bottom end ofthe second joint of production tubing and into the second joint ofproduction piping, so that the sealing element is in frictionalengagement with the inner wall of the second joint of production piping.9. The process as claimed in claim 8 further comprising checking thedownhole pressure by means of a pressure gauge attached to the pressuregauge fitting of the casing degasser tool.
 10. The process as claimed inclaim 8 further comprising bleeding built up pressure from the wellboreby attaching a hose or pipe to the pressure release fitting of thecasing degasser tool and allowing the hydrocarbons to flow into a flarestack, a tank or a pit.
 11. The process as claimed in claim 8 furthercomprising testing well production capability by means of a flow proverattached to the pressure gauge fitting of the casing degasser tool. 12.A process for running joints of production piping into a wellborecontaining flowing hydrocarbons, comprising: (a) positioning a casingdegasser tool as claimed in any of claims 1 to 7 inside a first joint ofproduction piping to be lowered into the well bore, the first joint ofproduction piping having an inner wall, such that the sealing element ofthe casing degasser tool is in frictional engagement with the inner wallof the first production piping; (b) lowering the first joint ofproduction casing into the wellbore; (c) adding additional joints ofproduction piping to the first joint of production piping until all thejoints of production piping have been added; (d) attaching a pullingdevice to the connection means of the casing degasser tool; and (e)pulling the casing degasser tool through the joints of production pipingto the surface of the well.
 13. The process as claimed in claim 12further comprising checking the downhole pressure by means of a pressuregauge attached to the pressure gauge fitting of the casing degassertool.
 14. The process as claimed in claim 12 further comprising bleedingbuilt up pressure from the wellbore by attaching a hose or pipe to thepressure release fitting of the casing degasser tool and allowing thehydrocarbons to flow into a flare stack, a tank or a pit.
 15. Theprocess as claimed in claim 12 further comprising testing wellproduction capability by means of a flow prover attached to the pressuregauge fitting of the casing degasser tool.